1. Field of the Invention
The present invention relates generally to spindle motors and, more particularly, to a spindle motor, in which the number of parts is reduced, and the yield rate of which is increased.
2. Description of the Related Art
As well known to those skilled in the art, a spindle motor is a device which is mounted on an optical disk drive to drive a turntable, thus rotating a disk mounted on the turntable. Generally, as shown in FIG. 2, a spindle motor 200 includes a rotary unit 201 and a stationary unit 205.
The rotary unit 201 is the rotating part of the motor 200, and includes a rotating shaft 211, a rotor cover 221, and a magnet 231.
The rotating shaft 211 functions to rotate a turntable (not shown).
The rotor cover 221 serves to rotate the rotating shaft 211. A shaft fitting hole 222 is formed in the center of the rotor cover 221 so that the rotating shaft 211 is fitted into the shaft fitting hole 222. An oil discharge preventing piece 223 is mounted to an end of the shaft fitting hole 222 to prevent oil from being discharged from a bearing 215. Further, the rotor cover 221 extends in a circumferential direction, and an edge of the rotor cover 221 is bent downwards to cover a stator 235.
The magnet 231 forms a magnetic field, and is secured to an inner wall 224 of the rotor cover 221.
The stationary unit 205 is the fixed part of the motor 200, and includes the bearing 215, a holder 225, the stator 235, and a base 245.
The bearing 215 rotatably supports the rotating shaft 211.
The holder 225 holds the bearing 215 to secure the bearing 215 to a predetermined position. The bearing 215 is firmly coupled to the inner circumferential surface of the holder 225.
The stator 235 forms an electric field when external power is applied to the stator 235. The stator 235 is firmly coupled to the outer circumferential surface of the holder 225.
Further, a holding magnet 236 is coupled to the upper portion of the inner circumferential surface of the stator 235 via a back yoke 237, and holds the disk to prevent the disk from being damaged when the disk (not shown) is rotated.
The base 245 functions to support the entire motor 200. The central portion of the base 245 extends outwards, thus defining an insertion hole 246. A printed circuit board 247 is mounted on the upper surface of the base 245, and controls a signal for driving the motor 200.
However, the conventional spindle motor 200 constructed as described above is problematic in that the motor 200 is provided with the back yoke 237 to install the holding magnet 236, and is provided with the oil discharge preventing piece 223 to prevent oil from being discharged from the bearing 215 to the outside, so that the number of parts is increased, the manufacturing process is complicated, and thereby the yield rate is reduced.